product key

Here's how to activate by phone..Activate Windows 7 by Phone

Did you purchase the 7 Home Premium Upgrade?
I did and product key is inside the plastic box it came in.

You will have to call and convince MS about your HD going kaput and see if they will activate the key.
Best of luck!

You could try this link might work for you. Calling will always work but sometimes requires a small amount of patience. Good luck to you with your problem.
http://www.microsoft.com/genuine/sel...tructions.aspx

Did you actually get to speak to an activation advisor?

Both the Internet and phone method of activation are the same. With the first method, the data is transferred automatically between your machine and the server. In the second method, the same data is transferred, but instead of it being automatic, it is done manually via the telephone keypad and by you typing the resulting activation code into your computer. If the Internet method fails, then the phone method will also fail, given that it is just an alternative means of transferring the same information and data. However, if you hang on to the line until an advisor answers you, you should be able to activate without any problems. MS knows that hardware will fail, and will do its best to assist you with activation issues. In most cases, this is not a problem but it does require the intervention of an activation advisor who can reset the server (remove your existing data) so that you can successfully activate.